Hi discobob,

What exactly does the graph of cos(x) look like from 0 to 360 degrees?

It starts at cos(0)=1,

drops to zero at 90 degrees,

goes down to -1 at 180 degrees,

comes back up to zero at 270 degrees,

reaches 1 again at 360 degrees.

Therefore there is an interval from zero to where cos(x) is

where

and similar at the other end of the period.